The present invention relates to the treatment of airborne allergens.
Various allergens are known which are transported through the air to trigger a human reaction. For example, it has been known for a long time that house dust can trigger allergenic reactions in humans, such as asthma and rhinitis. It was reported, as early as 1928 that it was the dust mites in the dust that were the primary source of the allergenic response, but it was only in the 1960""s that researchers appreciated its significance.
It is believed that the faeces of the house dust mite, Dermatophogoides farinae (known as Der-f) and Dermatophagoides pteronyssinus (known as Der-p) trigger the immune response of the body, thereby giving rise to well known allergenic symptoms.
One way to overcome these allergenic responses has been to vacuum clean surfaces, such as carpets, that contain the dust mites and their faeces thoroughly and often, but that is both time consuming (it has to be regularly done to ensure an allergenic free environment) and is very dependant on the efficiency of the vacuum cleaner and filter bag used, e.g. micron filter bags or two layer vacuum bags.
An alternative method of creating an allergen-free environment has been to denature the allergen, for example, by using an allergen denaturant applied to airborne allergens by means of an aerosol spray device. Such a device produces an aerosol spray when activated and this spray may be targeted at any space which is to be treated.
The allergens to be treated are airborne particles and the use of a known aerosol spray device results in a low collision rate between the allergen denaturant and the airborne allergens. The practical consequence of such a low collision rate is that the allergen denaturant must be used in a high amount in order to be effective. There may be other consequences such as, in the case where the aerosol spray composition includes a perfume or fragrance, a strong perfume smell or a limited fragrance choice.
Other allergens which are problematic are cat allergens (Fel-d) and cockroach allergens (Bla-g). These can be denatured using an allergen denaturant for the specific allergen applied using an aerosol spray device.
An aerosol spray type device would be of improved efficiency if the spray droplets had a greater collision rate with the allergen particles and if the droplets could wet the surface of the allergen particles. We have now developed an improved method of denaturing or deactivating airborne allergens.
According to the present there is provided a method of denaturing or deactivating an airborne allergen comprising directing at the airborne source of the allergen liquid droplets from a spray device containing a liquid composition which includes an allergen denaturant or allergen deactivant, the method comprising imparting a unipolar charge to the said liquid droplets by double layer charging during the spraying of the liquid droplets by the spray device, the unipolar charge being at a level such that the said droplets have a charge to mass ratio of at least +/xe2x88x921xc3x9710xe2x88x924 C/kg.